Process of treating photographic paper.



cairn singles JOSEPH soar, or WYNEGI-IEM, AND

. ASSIGNORS 'ro scorers ANONYME WERP. BELGIUM.

ATENT PROCESS OF TREATING PHOTOGRA PHIC PAPER.

1,010,200. No Drawing.

To all whom 'it may concern.

Be it known that we, JOSEPH SURY, a sub ject' of the King of Belgium, residing at \Vyneghem, Belgium, engineer chemist, and EDMOND BASTYNS, a subject of the King of Belgium, residing at 29 Rue des Tanneurs, Antwerp, Belgium, druggist, have invented certain new and useful Improvements in Frocesses of Treating Photographic Paper, ofwhich the following is a specification.

This invention relates to the printing on. paper of photographs in colors using three, negatives obtained by the three-color process, the paper being theonly and final basis and the process used", three successive pr'intings after a suitable sensitizing of the paper. Generally the printing of photographs in colors is obtained by superposing 'two positive plates with a film,

three separately printed phototypes (either third image interposed, or three carbon prints transferred one on the other).

In this invention an ordinary paper (preferably a paper, retaining its initial size notwithstanding repeated wetting and drying) is coated with a'sensitizing solution giving a blue print (for instance ferro-prussiate solution) on which the plate taken with the red screen is printed. After washing and drying a second sensitizing is proceeded with but this time with a solution giving a yellow print (for instance bichromated gum in' which a suitable yellow color has been mixed) The plate taken with the green screen is next printed, the print being subsequently washed and dried. The picture is green at the places where the blue printing and the yellow are superposed. A third sensitizing with a; suitable red solution (for instance bichromatized gum in which a suitable red pigment hasheen mixed) is followed by the printing of the plate taken with theblue-violet screen. This last printing gives all the intermediate tints between red and violet according to the presence more or less marked of each of the three fundamental colors. The three successive prints are thus made one on the top of the other by' superposition.

The inventors'are aware that in certain hichromated gum processes several successive printings are sometimes used but the means Specification of Letters Patent.

Application filed March 11,

consequently the 'iste'r', that is hearing the shrinkage thereof Patented Nov. 28, 1911.

1909. Serial No. 482,791.

employed as well as the result arequite different. In the bichromatedggum process a monochrome print is intensified, one negative being employed, while in the present case three prints each of" a different color are printed successively one on the top of the other by superposition from three corresponding negatives with the result that a polychrome picture is obtained.

Any kind of printinggiving monochrome pictures ofa particular color can be used and the order of superposing them is indifferen't.

Regarding the paper it was found that after the ferroprussiate.pr inting was done the d'rying'of the bichromated m coating resulted in a shrinking of the paper and two pic'tfires did not reg to say the corresponding points'of two negatives did not coincide in the printing. In order to avoid this shrinkage, the paper. is first put in a solution of formic aldehyde or a tanning solution. After drying, the back of the paper is coated with a solution of gumo-r sugar in water (gum, dextrin, sugar, glucose or othel similar product). This has the effect of making the paper shrink before the ferroprussiate printing is done, to the same extent as it will shrink when drying after the coating with the yellow or red gum solution. The three negatives will therefore register exactly. This permits ofthe paper being sold ready for the blue printing.

'WVhat we claim as our-invention and desire to secure by Letters Patent is 1. A process of treating photographic paper for the pur ose of preventing'the uring printing consisting in treating the paper with a tannin solution, drying the treated paper and then treating the paper, with. a gain solution.

2-. A process of treating. photographic paper for the purpose of preventing the shrinkage thereof during printing consist-- ing in treating the papcr with a tannin-splution such as formic aldehyde, drying the treatedpaper and then treating witha gum solution.

3. A process of treating hotographic paper for preventing the shrin age thereof consisting in treating the paper with a tanthe paper 1 iiinsolution; dryin the treated. paper and In testimony whereof We have hereunto 10 coating the backo the papen with a gum signed our names to this specification in the j paper for preventing the shrinkage thereof solution. 1 .7 presence of two subsci'ibing witnesses.

ces of treating photographic JOSEPH SURY LA pro consisting intreating the paper with a tan- EDMOND BASTYNS? nin solution suches formic aldehyde, dry; Witnesses:

ing the treated page a nd'ooatlin e ba ck ALEXIEMUNSPRY ofjth'e paper with a-u so1ution. Dli LERs f 

